The invention relates to a motion-compensated picture signal interpolation apparatus which may be used to create additional lines or fields for improving the display quality of a picture signal. The invention further relates to a television signal receiver comprising such an interpolation apparatus.
European Patent Application EP-A-0,474,287 (U.S. Ser. No. 751,290, filed Aug. 29, 1991, allowed) (PHN 13,443) describes a line number doubler in which a median filter reduces artifacts in an interpolated line obtained by motion-compensated interpolation using a single motion vector per pixel or per block of pixels.
When very complex and fast movements in the image cannot be estimated correctly, for example, because they are outside the estimator range or because the velocity field is very inconsistent, estimated motion vectors are incorrect and a motion-compensated interpolation based on these motion vectors yields erroneous results. Subjectively, artifacts arising from such incorrect motion vectors are very disturbing at transients and in the neighborhood of stationary objects, since they tend to be concentrated in an isolated, conspicuous spot on the screen, especially when there is high spatial detail.